1. Field of the Invention
The present invention relates generally to the generation of hydrogen gas and the employment of it as a combustible fuel. More particularly, the present invention relates to an “on-demand” chemical system for producing hydrogen gas and using it for propulsion, wherein critical elements are recovered and recycled.
2. Description of the Related Art
It has long been recognized by those skilled in the art that hydrogen, the most abundant element in the universe, is relatively cheap and plentiful. Long recognized as a basic constituent of water, many have dreamt of its use as a fuel. Accordingly, the prior art reflects numerous diverse attempts at recovering or generating hydrogen, and a virtual plethora of patents directed to propulsion systems and energy storage or transfer systems involving it.
U.S. Pat. No. 3,943,719. discloses a power system comprising a reactor in which a hydride absorbs hydrogen at low pressure and low temperature, and then heating the hydride at constant volume so as to release large quantities of hydrogen at high temperatures and pressure. This released hydrogen is used to produce power and yield refrigeration. Electrical power can be generated by expanding the released hydrogen through a turbine or other power producing devices.
U.S. Pat. No. 4,005,185 issued Jan. 25, 1977 discloses a method for generating hydrogen using metallic zinc within an aqueous solution, preferably ammonium carbonate.
U.S. Pat. No. 4,055,962 discloses a hydrogen-hydride absorption system comprising a sequential method of reversibly combining hydrogen with a hydride-forming material, heating the hydride at constant volume, and means for conveying hydrogen between the reactors. In the power or heat pump cycle, the hydride in a first reactor is heated to desorb hydrogen gas. The gas flows to a second hydride bed in a second reactor where it is absorbed at a temperature lower then the temperature of desorption of the first hydride bed. Absorption of the hydrogen by the second reactor releases the heat of absorption. This heat of absorption is typically removed by a heat exchanger. In the heat pump mode of operation, the above cycle is sequentially repeated through a series of reactors so that the heat of absorption is sequentially added to the heat exchange fluid.
U.S. Pat. No. 4,085,709 issued Apr. 25, 1978 discloses a fuel system for vehicles that generates hydrogen gas electrically and stores it on board the vehicle for combustion. The system includes a gas cylinder, an electrolyzer connected to the gas cylinder, and a power supply connected to the electrolyzer, and a gas storage cylinder.
U.S. Pat. No. 4,090,361 discloses improved-power cycles for using the hydride-dehydride-hydrogen (HDH) power cycle to produce hydrogen gas continuously at high pressure and elevated temperatures. This gas can be used to produce power and refrigeration. The hydrogen gas can be passed directly to an expansion device, such as a turbine, or the hydrogen gas can be the working fluid used to transfer heat to a secondary system. Terry discloses using the HDH cycle to continuously produce hydrogen gas to drive an expansion device such as a turbine.
U.S. Pat. No. 5,228,529 issued Jul. 20, 1993 employs magnesium anodes in renewable fuel cells that produce hydrogen gas on demand for powering a vehicle. In operation the magnesium anode is converted into magnesium hydroxide precipitate, which is removed and collected for recycling. The magnesium anode and electrolyte is replaced to recharge the fuel cell.
U.S. Pat. No. 5,286,473 issued Feb. 15, 1994 discloses a system reacting an alkali metal with an ionizable hydrogen compound selected from the group consisting of hydrochloric acid, water or mixtures thereof to produce hydrogen and an alkali metal chloride or alkali metal hydroxide, depending upon whether hydrochloric acid or water is used to react with the alkali metal. The alkali metal chloride is recycled. The hydrochloric acid is recycled to produce hydrogen by reaction with the alkali metal. The aluminum hydroxide formed can be electrolyzed to aluminum metal and water to provide a method of recovering aluminum metal from aluminum scrap which previously has not be readily recyclable.
U.S. Pat. No. 5,293,857 issued Mar. 15, 1994 shows a combination wherein hydrogen gas fuel is combusted within an internal combustion engine. The proportion of hydrogen to oxygen is approximately 2:1, and the density of hydrogen is regulated so that the burn rate of the combined gas mixture approximates that of a fossil fuel.
U.S. Pat. No. 5,634,341 issued Jun. 3, 1997 and U.S. Pat. No. 5,867,978 issued Feb. 9, 1999 disclose related systems for generating hydrogen gas from a charge of fuel comprising lithium, aluminum or alloys thereof. The fuel is heated until molten, and sprayed with water within a pressure vessel. The process may be employed with either a Rankine-cycle engine or a hydrogen-oxygen fuel cell system.
U.S. Pat. No. 5,728,464 issued Mar. 17, 1998 discloses an on-demand hydrogen generation system for propulsion. Sodium pellets are exposed to water to generate hydrogen.
U.S. Pat. No. 5,830,426 issued Nov. 3, 1998 illustrates an aqueous hydrogen generation process wherein an electrical vehicle utilizes a hydrogen-air fuel cell to power electrical drive motors. Hydrogen fuel is supplied on demand by a reactor bed of iron particles that reacts with water in the presence of an alkali hydroxide catalyst. Potassium hydroxide in a range of concentrations between 50 to 60 percent by weight is preferred. Hydrogen gas generated in situ is stored within a compartment containing iron materials. Iron oxide produced during hydrogen generation may be recovered and recycled.
U.S. Pat. No. 5,865,262 issued Feb. 2, 1999 discloses a self-propelled hydrogen fuel system. A hydrogen gas tank receives gas from a chemical reactor equipped with a catalyst. Alcohol is vaporized in an heat exchanger, reacting with the catalyst in the chemical reactor and forming hydrogen gas and acetic ether, which are stored in appropriate tanks.
U.S. Pat. No. 5,867,978 issued Feb. 9, 1999 discloses a system for generating hydrogen for generating hydrogen gas from a charge of fuel selected from the group consisting of lithium and alloys of lithium and aluminum. The charge of fuel is placed into an enclosed vessel, then heated until it is molten. A reactant consisting of water is introduced into the vessel, as by spraying from a nozzle, for reaction with the charge of fuel resulting in the production of hydrogen gas and heat which are withdrawn from the vessel. Prior to initiation of the process, an inert gas atmosphere, such as argon, may be imparted to the interior of the vessel. A sufficiently large mass flow of the reactant through the nozzle is maintained to assure that there be no diminution of flow resulting from the formation on the nozzle of fuel and chemical compounds of the fuel. Optimum charges of the fuel are application specific and the ranges of the constituents are dependent upon the particular use of the system. The process and apparatus of the invention may be incorporated into a Rankine cycle engine or into a hydrogen oxygen fuel cell system.